Well pumps



G. K. ROEDER July 9, 1963 WELL PUMPS 4 Sheets-Sheet 1 Filed May 21, 1962 INVENTOR George K. Roea'er ATTORNEYS G. K. ROEDER July 9, 1963 WELL PUMPS 4 Sheets-Sheet 2 Filed May 21, 1962 INVENTOR George K Roeder ATTORNEYS G. K. ROEDER July 9, 1963 WELL PUMPS 4 Sheet s-Sheet 3 Filed May 21, 1962 FIG.5

INVENTOR George K. Raeder ATTORNEYS FIG.3D

G. K. ROEDER July 9, 1963 WELL PUMPS 4 Sheets-Sheet 4 Filed May 21, 1962 R f 0 5 mwwwwm WW Kw m 3 III E r w ,f 2 W \n\u\r .II II R G K m H e F m w t w a w X aw ATTORNEYS 3,096,717 Patented July 9, 1963 ice 3,096,717 WELL PUMPS George K. Roeder, Odessa, Tex., assignor to Roeder Hydraulics, Inc., Odessa, Tern, a corporation of Texas Filed May 21, 1962, Ser. No. 196,091 16 Claims. (Cl. 103-46) This invention relates to new and useful improvements in well pumps.

The invention is particularly concerned with well pumps as used in water wells, and in particular in oil Wells, in which the pump is operated by rods rcciprocated from the ground surface, the pump being usually set in a conventional seat or shoe provided in the well tubing, and the production of fluid being upwardly from the producing formation through the tubing to the ground surface.

In this type of well pump it is desirable to have a relatively long and relatively slow pump stroke for the purposes of producing more fluid per stroke and for reducing wear upon the elements of the well pump as well as the rods which operate the pump, conventionally termed sucker rods. The achieving of this objective, however, usually involves the use of quite large pumping units at the ground surface in order to furnish the desired long pump stroke. Such pumping units, if of the pump jack type, are necessarily quite large and expensive, or else, quite expensive and complex hydraulic pumping devices must be employed.

Another problem in wells pumped with sucker rods is the alternate tensioning and slackening of the sucker rods which may be quite a few thousand feet in length, with the resultant wear and fatigue and ultimate failure of the sucker rods together with their impact against the walls of the well tubing and possible wear or damage of the tubing.

It is, therefore, a principal object of this invention to provide an improved well pump by means of which a sucker rod stroke of a given length is caused to move a pumping piston through a somewhat longer stroke, thus achieving the benefits of long stroke pump operation while utilizing a relatively short sucker rod stroke.

An additional object of the invention is to provide an improved well pump by means of which the sucker rods are constantly under tension so as to avoid undue fatiguing and wear of the sucker rods and the well tubing.

A still further object of the invention is to provide an improved well pump having a unique and beneficial sealing means for sealing between two relatively movable elements.

Yet another object of the invention is to provide an improved well pump in which power is imparted to a body of power fluid by one piston undergoing a stroke of given length, and the power fluid is caused to drive a motor piston through a stroke of greater length, and in which, unique provision is made for reducing or increasing the volume of the power fluid as the operation of the pump may require and through the utilization of an automatically functioning valve.

Other and more particular objects of the invention will be apparent from a reading of the following specification.

A construction designed to carry out the invention will be hereinafter described, together with other features of the invention.

The invention will be more readily understood from a reading of the following specification and by reference to the accompanying drawings, wherein examples of the invention are shown, and wherein:

FIG. 1 is a diagrammatic view of a well pump constructed in accordance with the invention and showing the pump commencing its upward stroke,

FIG. 2 is a view similar to FIG. 1, showing the well pump commencing its downward stroke,

FIG. 3 is a vertical view, partly in elevation and partty in section, of the upper extremity of a well pump constructed in accordance with this invention,

FIG. 3-A is a continuation of FIG. 3,

FIG. 3-B is a continuation of FIG. 3-A,

FIG. 3-0 is a continuation of FIG. 3-B,

FIG. 3D is a continuation of FIG. 3-C,

FIG. 3E is a continuation of FIG. 3-D showing the lower extremity of the well pump,

FIG. 4 is a vertical, sectional view of the relief valve structure, showing the valve in an open position,

FIG. 5 is a vertical view, partly in elevation and partly in section, of the lower portion of the motor piston as it begins its upward stroke,

FIGS. 6, 7 and 8 are enlarged, horizontal, cross-sectional views taken upon the respective lines of FIGS. 3, 3-A and 3-H,

FIG. 9 is a diagrammatic view of a modified form of the well pump, showing the well pump commencing its upward stroke,

FIG. 10 is a view similar fied form of the well stroke,

FIG. 11 is an enlarged, vertical sectional view of the liquid equalizing valve of the modified form of the pump, and

FIG. 12 is a horizontal, cross-sectionai view taken on the line 12-12 of FIG. 11.

In the drawings, and referring specifically to FIGS. 1 and 2, the numeral 10 designates a well tubing which forms no part of the present invention and which will carry a conventional seating nipple or shoe in which the pump may be seated or anchored for secure positioning in the well bore. The pump includes a pump barrel 11 at its lower end carrying on its lower extremity a hold down and first sealing means 12 which may be a combination unit or two separate structures secured to the pump barrel and which, by engagement with the seating shoe anchors and secures the pump barrel and the elements connected thereto within the well tubing. A motor barrel 13 of lesser internal diameter than the pump barrel 11 is connected to and extends upwardly from the pump barrel, telescoping the interior of a power barrel 14 which surrounds the motor barrel and is suitably connected at its upper end to sucker rods 15 through which the pump is operated from the ground surface by conventional pumping equipment. The sucker rods also form no part of this invention.

A pump piston 16, carrying an upwardly opening check or traveling valve 17 slidably engages the interior of the pump barrel 11 and is connected by a tubular mandrel or connecting element 18 to a motor piston 19 carrying an upwardly opening check or traveling valve 20 and slidably engaging the interior of the motor barrel 13. A motor fluid seal or second sealing means 21 is carried by the motor barrel 13 near its lower end and slidably engages the exterior of the tubular mandrel 18. The power barrel 14 carries a third sealing means 22 at its lower end which slidably engages the exterior of the motor barrel 13, and the motor barrel carries a power piston 23 at its upper end slidably engaging the interior of the power barrel 14. The upper end of the power barrel 14 is open to the upper portion of the tubing through ports 24.

An outwardly opening, spring pressed check valve 25 immediately below the power fluid seal 23 communicates between the interior of the motor barrel 13 and the interior of the power barrel 14, and ports 26 open from the interior of the power barrel 14 into the interior of the motor barrel 13 between the motor fluid seal 21 and the to FIG. 9, showing the modipump commencing its downward motor piston 19. Further, the bore of the tubular mandrel 18 opens through ports 27 into the interior of the pump barrel 11. It is to be noted that the exposed or effective working area on the lower side of the motor piston 19 is somewhat less in area than the effective or working area exposed on the upper side of the power fluid seal 22, and that the working area of the pump piston 16 is oftentime larger than the working area of the motor piston 19. Now, as the power barrel 14 is drawn upwardly by the sucker rods 15, the power seal 22 will be moved upwardly, and since the power fluid present within the power barrel 14 is prevented from escaping at its upper end by the power piston 23 and the valve 25, the fluid will be forced through the ports 26 to move the motor piston 19 upwardly along with the mandrel 18 and the pump piston 16. Since the liquid is not compressible, and since the seal 22 offers a greater working area than the motor piston 19, the motor piston 19 will be moved upwardly through a stroke greater than the upward stroke of the power barrel 14, thereby obtaining the desirable result of a pumping stroke somewhat greater in length than the vertical stroke of the sucker rods 15.

In the operation of the pump and assuming that it has been properly seated and anchored in the well with the seal 12 closing off the lower annular portion thereof, the pump and tubing is desirably filled with liquid, preferably with oil which will be held against draining downwardly through the pump due to gravity closure of the valve 17.

The upward movement of the pump piston 16 by means of the mandrel 18 forces the liquid within the pump barrel 11 through the ports 27 and upwardly through the check valve and the ports 24 into the tubing above the pump, and since the pump piston 16 is often time of a larger area than the motor piston 19, increased volumes of fluid will necessarily be pumped upwardly into the tubing.

As the pump structure reaches the upper end of its stroke, the valve 20 will close, and as the pump structure commences its downward stroke, the valve 17 will open. At this point, the pressure on both sides of the pump piston 16 will be formation pressure or bottom hole pressure, and the pressure on the upperside of the power seal 22 will be that on the entire upperside of the motor piston 19, thus overcoming the pressure on the underside of the power seal 22 which will be the hydrostatic head of the fluid in the tubing above the pump. The pressure across the entire area of the upperside of the motor Piston 19 will be that of the hydrostatic head of the fluid standing in the tubing. This is sufficient to force the power barrel 14 downwardly and to force the mandrel 18 and the pump piston and motor piston 19 downwardly while at the same time retaining a tension on the rods 15. Thus, the pump does not return to the lower end of its stroke through gravity alone but through the effect of the hydrostatic head of fluid existent within the tubing to the surface of the ground which is considerably greater than the bottom hole pressure or formation pressure existent below the pump. The total area acted upon the hydrostatic head forcing the pump to the lower end of its stroke is the difference between the top and bottom areas of the motor piston 19. Upon the return of the pump to the lower end of its stroke, the upward stroke will again commence and the operation will be repeated. In this manner, the sucker rods are held under a tension on both the upward and the downward strokes and the harmful and undesirable results of alternate tensioning and slackening of the sucker rods is avoided.

As will appear more fully hereinafter, if the action of the power barrel 14 tends to force the motor piston 19 any appreciable distance beyond the upper limit of its stroke, the motor piston functions to open the valve 25, permitting power fluid to bleed thcrethrough into the upper end of the motor barrel 13 and terminating any further upward driving of the motor piston 19 thereby. Also, as the power barrel 14 nears the lower end of its stroke, if there should be any lack of sufficient liquid within the power barrel 14 to permit full downward stroking, the valve will be pulled open due to the created vacuum conditions and additional liquid will be drawn into the interior of the power barrel to prevent the occurrence of a short stroke action.

Turning now to a more specific embodiment of the invention which is shown in FIGS. 38 the pump is provided at its upper end with an open upper cage 28 having an axial screw-threaded pin 29 at its upper end for connection to conventional sucker rods and provided with lateral discharge ports 30 through which fluid may flow from the interior of the cage. The cage carries a screw-threaded pin 31 coupled to the upper end of an elongate tubular power barrel 14' having scrcw-threadedly connected to its lower end the power seal or third sealing means 22. The power piston 23', in the form of an elongate tubular pistion 32 having a plurality of circumferential sealing rings 33, has a snug sliding fit within the interior of the power barrel 14' and carries on its lowe end a reduced, screwthreaded pin 34 received in the screw-threaded box 35 of the relief valve assembly 25', the assembly 25 having an external diameter less than that of the piston 32 so as to form an annulus 36.

The motor barrel 13, having the same outside diameter as the relief valve assembly 25, is screw-threadedly connected on to the lower end thereof and extends downwardly into connection with a coupling 37 having screwthreaded pins on both its upper and lower ends. The ports 26' are formed in the lower extremity of the motor barrel 13 immediately above the coupling 37.

An extension 38 of the motor barrel 13' is screwthreadedly connected to the lower end of the coupling 37 and extends downwardly through the power barrel 14' and through the power seal 22' in sliding engagement therewith to an enlarging coupling 39 and is screwthreadedly connected to the upper end thereof. The coupling 39 is of approximately the same external diameter as the seal 22' and the power barrel 14, and receives on its lower end in screw-threaded relationship the pump barrel 11' which extends downwardly through a screwthreaded collar 40 by which it is connected to the combined sealing means and anchor or hold down 12 which is of conventional construction.

Slidably engaging the interior of the motor barrel 13' and disposed therein below the relief valve assembly 25', is the motor piston 19 in the form of an elongate tubular plunger or piston 41 carrying a plurality of external circumferential sealing rings 42 and a conventional open cage traveling valve assembly 20 at its upper end. The lower end of the plunger 41 is reduced as indicated at 43 to ensure an internal flow space at all times for fluid entering through the ports 26' and is connected at its lower end to the tubular mandrel 18' extending downwardly into the pump barrel 11' and having connected to its lower end the pump piston 16 in the form of an elongate plunger 44 carrying a plurality of external, circumferential sealing rings 45 slidably and sealingly engaging the interior wall of the pump barrel 11'. The mandrel 18 is connected to the plunger 44 through a conventional coupling 46 which carries the ports 27', and the plunger 44 carries on its lower end the conventional traveling valve assembly 17'.

The relief valve assembly 25 includes a body 47 carrying the upstanding internally screw-threaded box 35 which receives the depending pin 34 of the plunger 32 and is smaller in diameter than the plunger so as to maintain the annulus 36 between the body 47 and the power barrel 14. The body 47 has a depending screw-threaded pin 48 to which the upper end of the power barrel 14' is connected and has an axial bore 49 extending upwardly from its lower end to a point adjacent the upper end of the body 47, the bore being screw-threaded at its lower end for receiving a valve seat body 50 having a reduced screw-threaded pin 51 on its upper end. The valve seat body 50 has an axial bore 52 extending from the upper end of the pin 51 into the lower portion of the body 50 and adjoined by a reduced bore 53 extending to the lower end of the body 50. A valve seat 54 is formed at the upper end of the bore 52, and a radial port 55 opens from the interior of the motor barrel 13' into the bore 52.

A valve 56 is adapted to engage the seat 54 and carries an elongate depending stem 57 projecting downwardly through the bore 53 into the interior of the motor barrel 13', a coiled spring 57 confined in the upper portion of the bore 49 between the upper end thereof and the valve 56 constantly urging the valve toward the seat 54. A second radial port 58 opens from the bore 49 above the valve seat 54 into the annulus 36 and thus into the interior of the power barrel 14'.

As previously noted, the relief valve structure functions both to discharge excess liquid from the annulus 36 between the power barrel 14' and the motor barrel 13 as Well as to supply additional liquid to this space when such is required. Upon the downward stroke of the power seal 22', should there be insuflicient liquid in the annulus 36 to permit completion of the downward stroke, vacuum conditions would come into existence within the annulus 36 pulling the valve 56 away from the seat 54 and permitting liquid to enter the annulus 36 through the ports 55 and 58 and the bore 49. On the other hand, should the motor piston 41 reach the upper end of its stroke before the power seal 22' reaches the upper end of its stroke, the upper end of the cage assembly will engage the shank 57 of the valve 56, opening the valve and permitting liquid to escape from the annulus 36 through the ports 58 and 52 and the bore 49. The rehef body 47 is further provided with a plurality of longitudinal ports 59 extending from the interior of the motor barrel 13' into the interior of the plunger 23 for upward passage of liquid being pumped upwardly by the pump piston 16'.

The motor fluid seal or second sealing means 21' is uniquely constructed and includes an outer tubular spacer or liner 60 of relatively thin-walled construction fitting within the bore of the extension barrel 38 of the motor barrel 13' and abutting the coupling 37 at its upper end and the coupling 39 at its lower end. inwardly of the liner 60 is a second, tubular, floating liner 61 having a snug sliding fit with the outer surface of the mandrel 18' so as to provide a seal therewith. The floating liner 61 is less in length than the distance between the couplings 37 and 39, and hence, is free to undergo limited longitudinal movement with the mandrel 18 as the latter reciprocates, such movement being due to the snug sealing engagement between the floating liner 61 and the mandrel, such movement reducing to some extent wearing between the abutting faces of the mandrel and the liner. For sealing between the floating liner 61 and the fixed liner 60, the floating liner is formed with a pair of peripheral grooves 62 in its medial portion which receives sealing O-rings 63 engaging the inner wall of the fixed liner 60 to provide an effective and efficient seal resistant to leakage as relative movement between the fixed liner and the floating liner occurs.

As previously noted, the power seal 22' is connected to the lower end of the power barrel 14', and is in the form of an elongate, thick-wall cylinder 64 having the same outside diameter as the power barrel 14' and the pump barrel 11 and being formed with a reduced upstanding screw-threaded pin 65 by which it is screwthreadedly connected to the lower end of the power barrel 14'. The inner periphery of the cylinder 64 has a snug sliding and sealing engagement with the outer surface of the motor barrel extension 38, so that as the power barrel 14' moves upwardly, the power seal 22', formed by the cylinder 64, moves upwardly over the outer surface of the extension 38 forcing liquid upwardly through the annulus 36 and the ports 26' into the space defined by the reduced portion 43 of the plunger 41 which forms the motor piston 19', driving the motor piston upwardly Within the motor barrel 31', as illustrated in FIG. 5. As indicated at 66 in FIG. 5, this upward movement of the motor piston draws the mandrel 18 upwardly, which may cause the floating liner 61 to undergo limited vertical movement so as to come into engagement with the lower end of the coupling 37. Normally, however, the pressure above the liner will hold it in its lower position. The liner structure allows the liner to shift laterally and even tilt slightly to conform to the mandrel and the motor barrel at the same time. In all other respects, the operation of the detailed embodiment of the invention is the same as that previously described in connection with the description of the diagrammatic illustration of the pump structure.

A modified form of the invention is illustrated in FIGS. 9 through 12 of the drawings, this form of the invention utlizing a working plunger as a power piston in contrast to the utilization in the first form of the invention of a working barrel with the power piston. In FIGS. 9 through 12 the numeral 67 designates the well tubing in which the pump is positioned, a pump barrel 68 being anchored in the tubing by the usual bottom anchor and packing member 69 and carrying at its upper end a sealing member 70 of the type previously shown at 21 in FIG. 3B, the sealing member sealing around the periphery of a tubular piston rod 71 carrying at its lower end the usual pump plunger or piston 72, there being an upwardly opening check valve 73 in the lower end of the tubular rod 71, and ports 74 opening from the interior of the rod 71 into the interior of the pump barrel 68.

A motor barrel 75 is connected to and mounted upon the upper end of the sealing member 70 and receives therein a motor piston 76 connected to the upper end of the tubular pump rod 71, an upwardly opening check valve 77 also being provided at the upper end of the tubular rod 71. The pump barrel 68 carries an upward extension 78 surrounding the motor barrel 75, and ports 79 open from the interior of the motor barrel 75 below the piston or plunger 76 into the annulus 80 between the motor barrel and the extension 78. At the top of the motor barrel 75, there is a coupling member 81 having a passage 82 extending from the interior of the motor barrel to the interior of the tubing 67, and a second passage 83 extending from the annulus 80 to the space above the motor barrel 75. An upwardly opening check valve 84 opens from the interior of the motor barrel 75 to the space thereabove.

A further extension 85, similar to the extension 78, extends upwardly from the coupling 81 to enclose a flow space 86 and carrying at its upper end a sealing member 87, again similar to the previously described sealing member 21, which receives in sliding and sealing engagement the depending tubular rod 88 of a power piston or plunger 89 disposed within a power barrel 90 extending upwardly from the sealing member 87. The pump rod 91, which is secured to the sucker rods depending downwardly from the ground surface, is received slidably in a sealing member 92 at the upper end of the power cylinder 90 and is secured to the power piston 89 and tubular rod 88 for reciprocating the same. Ports 93 open from the interior of the tubular rod 88 into the interior of the power barrel 90 above the power piston 89, and additional ports 94 open from between the seal 87 and power piston 89 from the interior of the power cylinder 90 to the interior of the tubing 67.

The power piston 89 has a greater working area than the motor piston 76, and the latter desirably has a smaller working area than the pump piston 72.

FIG. 9 illustrates diagrammatically the modified form of the pump at the commencing of its upward stroke. Assuming the structure to be filled with oil as previously pointed out to be desirable prior to commencing of the pumping operations, the rod 91 moves the power piston 89 upwardly in the power barrel 90 causing the liquid therein to flow through the ports 93 into the interior of the tubular rod 88 and through the chamber 86 and the passage 83 and the ports 79 into the interior of the motor barrel below the motor piston 76, thus forcing the motor piston 76 upwardly in the motor barrel. Because the working area of the power piston 89 is greater than that of the motor piston 76, the motor piston will be forced to undergo a stroke of somewhat greater length than that imparted to the power piston 89, and accordingly, the pump piston 72 will be drawn through the same somewhat longer stroke than that which the power piston 89 undergoes. As the pump piston 72 moves upwardly in the pump barrel 68, the check valve 73 will close and the fluid in the pump barrel above the piston 72 will be forced through the ports 74 and the interior of the tube 71 into the motor barrel 75 and directed with the liquid contents of the motor barrel above the motor piston 76 outwardly through the ports 82 and upwardly through the tubing 67 to the well surface. The ports 94 allow fluid to surge in and out of the space between the sealing member 87 and the power piston 89, and the flow passage 86 merely provides space for reciprocation of the tubular rod 88. Liquid will also surge back and forth from beneath the motor piston 76 to and from above the power piston 89. Similarly to the first described form of the invention, should the motor piston 76 tend to undergo too long a stroke, it will engage and open the valve 34 to permit fluid to escape downwardly through the check valve 84 and outwardly through the ports 82. rather than being forced into the space beneath the motor piston 76. Similarly, if there is insufficient liquid to permit the power piston 89 to reach the bottom of its stroke, the check valve 84 will be pulled open to permit liquid to enter through the ports 82 and pass upwardly through the tubular rod 88 and the ports 93 into the upper portion of the power barrel 90.

On the downstroke, as illustrated in FIG. 10, the upper side of the motor piston 76 will be exposed to the entire hydrostatic head in the tubing 67 whereas the underside of the pump piston 72 will be exposed only to formation pressure. Accordingly, the motor piston 76 will be forced downwardly, forcing the pump piston 72 downwardly, and by flowing fluid into the space above the power piston 89, also forcing the power piston 89 downwardly while maintaining the pump rod 91 under a degree of tension.

The details of the coupling 81 and check valve 84 as sembly are shown in FIG. 11 and include a coupling member 95 having an upstanding screwthreaded pin 96 for screwthreaded engagement with the lower end of the extension member and a depending screwthreaded pin 97 for screwthreaded engagement with the depending extension member 78. An axial recess 98 extends upwardly through the pin 97, communicating with the ports 82 at its upper end and being counterbored in its lower portion to form an internally screwthreaded box 99 for screwthreaded engagement with the upper end of the motor barrel 75. The passages 83 are spaced circumferentially around the coupling element and communicate be tween the upper and lower ends of the upper and lower pins 96 and 97, respectively. A check valve core 100 is confined within a ported cage 101 which encloses a spring 102 constantly urging the valve core 100 against the valve seat 103 formed in the upper end of an axial recess 104 extending downwardly from the upper end of the pin 96. A tubular valve stem 105 is connected to and extends downwardly from the valve core 100, having a radial port 106 disposed within the recess 104, and a second radial port 107 exposed to the interior of the motor barrel 75 so that fluid flow may pass from the recess 98 to the recess 104. The functioning of this check valve structure is as previously described.

The foregoing description of the invention is explanatory thereof and various changes in the size, shape and materials, as well as in the details of the illustrated construction may be made, within the scope of the appended claims, without departing from the spirit of the invention.

What I claim and desire to secure by Letters Patent is:

1. A well pump including,

a pump barrel,

a motor barrel,

first means for anchoring the pump barrel and the motor barrel in a well bore and sealing externally of the pump between the lower end of the pump barrel and the upper end of the motor barrel,

means for exposing the lower end of the pump barrel to the well bore below the first sealing means,

means for exposing the upper end of the motor barrel to the well bore above the first sealing means,

a pump piston in the pump barrel,

2. motor piston in the motor barrel,

an element connecting the pump piston and the motor piston and having a flow passage between the underside of the pump piston and the upperside of the motor piston,

means in the flow passage for preventing fluid flow downwardly from the passage to the underside of the pump piston,

means communicating the flow passage above the latter means with the interior of the pump barrel,

second sealing means slidably engaging the element connecting the pump piston and the motor piston for sealing olf between the pump barrel and the motor barrel,

a power barrel surrounding the motor barrel,

third sealing means carried by the power barrel and slidably engaging around the motor barrel,

means communicating the interior of the motor barrel above the third sealing means with the interior of the power barrel,

a power piston slidably engaging the power barrel and sealing between the power barrel and the motor barrel above the point of exposure of the interior of the motor barrel to the interior of the power barrel,

the power piston having a working area greater than that of the motor piston,

and means for preventing fluid flow downwardly from the interior of the motor barrel into the flow passage.

2. A well pump including,

a pump barrel,

a motor barrel,

first means for anchoring the pump barrel and the motor barrel in a well bore and sealing externally of the pump between the lower end of the pump barrel and the upper end of the motor barrel,

means for exposing the lower end of the pump barrel to the well bore below the first sealing means,

means for exposing the upper end of the motor barrel to the well bore above the first sealing means,

a pump piston in the pump barrel,

a motor piston in the motor barrel having a smaller working area than the pump piston,

an element connecting the pump piston and the motor piston and having a flow passage between the underside of the pump piston and the upperside of the motor piston,

means in the flow passage for preventing fluid flow downwardly from the passage to the underside of the pump piston,

means communicating the flow passage above the latter means with the interior of the pump barrel,

second sealing means slidably engaging the element connecting the pump piston and the motor piston for sealing off between the pump barrel and motor barrel,

a power barrel surrounding the motor barrel,

third sealing mean carried by the power barrel and slidably engaging around the motor barrel,

means communicating the interior of the motor barrel above the third sealing means with the interior of the power barre],

a power piston slidably engaging the power barrel and sealing between the power barrel and the motor barrel above the point of exposure of the interior of the motor barrel to the interior of the power barrel,

the power piston having a working area greater than that of the motor piston,

and means for preventing fluid flow downwardly from the interior of the motor barrel into the flow passage.

3. A well pump including,

a pump barrel,

a motor barrel,

first means for anchoring the pump barrel and the motor barrel in a well bore and sealing externally of the pump between the lower end of the pump barrel and the upper end of the motor barrel,

means for exposing the lower end of the pump barrel to the well bore below the first sealing means,

means for exposing the upper end of the motor barrel to the well bore above the first sealing means,

a pump piston in the pump barrel,

a motor piston in the motor barrel,

an element connecting the pump piston and the motor piston and having a flow passage between the underside of the pump piston and the upperside of the motor piston,

means in the flow passage for preventing fluid flow downwardly from the passage to the underside of the pump piston,

means communicating the flow passage above the latter means with the interior of the pump barrel,

second sealing means slidably engaging the element connecting the pump piston and the motor piston for sealing off between the pump barrel and the motor barrel,

a power barrel surrounding motor barrel,

third sealing means carried by the power barrel and slidably engaging around the motor barrel,

means communicating the interior of the motor barrel above the third sealing means with the interior of the power barrel,

:1 power piston slidably engaging the power barrel and sealing between the power barrel and the motor barrel above the point of exposure of the interior of the motor barrel to the interior of the power barrel,

the power piston having a working area greater than that of the motor piston,

a relief valve opening between the interiors of the motor barrel and the power barrel above the third sealing means and below the motor piston,

and mean for preventing fluid flow downwardly flrom the interior of the motor barrel into the flow passage.

4. A well pump as set forth in claim 1 wherein the second sealing means includes a fixed liner held against longitudinal movement and engaging the motor barrel,

a floating liner mounted to undergo limited longitudinal movement and sealingly engaging the element ionnesting the pump piston and the motor piston, and flexible sealing means between the fixed liner and the floating liner.

5. A well pump as set forth in claim 3, wherein the relief valve includes a body having a passage extending between the interiors of the motor barrel and the power barrel,

a valve seat in the passage,

a spring-pressed valve closing against the seat toward the motor barrel end of the passage,

and a shank on the valve extending into the motor barrel for engagement by the motor piston at the upper end of its stroke for unseating the valve and opening the passage.

6. A well pump including,

a power barrel vertically reciprocable in a well bore,

a power fluid seal carried by the lower portion of the power barrel,

a motor barrel within the power barrel having its exterior slidably engaged by the power fluid seal,

a power piston carried by the upper portion of the motor barrel and slidably engaging the interior of the power barrel,

a pump barrel rigidly connected to the motor barrel and disposed therebelow,

means for anchoring the pump barrel and the motor barrel in a well bore and sealing externally of the pump between the lower end of the pump barrel and the upper end of the motor barrel,

a motor piston in the motor barrel having a Working area less than that of the power piston,

a pump piston in the pump barrel,

a mandrel connecting the motor piston and the pump piston and having a flow passage extending from the upperside of the motor piston to the underside of the pump piston,

means communicating the flow passage with the interior of the pump barrel above the pump piston,

downwardly-closing valve means in the flow passage above and below the point of exposure of the flow passage to the interior of the pump barrel, and a motor fluid seal carried by the motor barrel and slidably engaging the exterior of the mandrel between the pump piston and the motor piston,

means communicating the interior of the motor barrel with the interior of the power barrel at a point between the motor fiuid seal and the motor piston.

7. A well pump including,

a power barrel vertically reciprocable in a well bore,

a power fluid seal carried by the lower portion of the power barrel,

a motor barrel within the power barrel having its exterior slidably engaged by the power fluid seal,

a power piston carried by the upper portion of the motor barrel and slidably engaging the interior of the power barrel,

a pump barrel rigidly connected to the motor barrel and disposed therebelow, means for anchoring the pump barrel and the motor barrel in a well bore and sealing externally of the pump between the lower end of the pump barrel and the upper end of the motor barrel,

a motor piston in the motor barrel having a working area less than that of the power piston,

a pump piston in the pump barrel having a working area larger than that of the motor piston,

a mandrel connecting the motor piston and the pump piston and having a flow passage extending from the upperside of the motor piston to the underside of the pump piston,

means communicating the flow passage with the interior of the pump barrel above the pump piston,

downwardly-closing valve means in the flow passage above and below the point of exposure of the How passage to the interior of the pump barrel,

and a motor fluid seal carried by the motor barrel and slidably engaging the exterior of the mandrel between the pump piston and the motor piston,

means communicating the interior of the motor barrel with the interior of the power barrel at a point between the motor fluid seal and the motor piston.

8. A well pump including,

a power barrel vertically reciprocable in a well bore,

a power fluid seal carried by the lower portion of the power barrel,

2. motor barrel within the power barrel having its exterior slidably engaged by the power fluid seal,

a power piston carried by the upper portion of the motor barrel and slidably engaging the interior of the power barrel,

a pump barrel rigidly connected to the motor barrel and disposed therebelow,

mean for anchoring the pump barrel and the motor 1 1 barrel in a well bore and sealing externally of the pump between the lower end of the pump barrel and the upper end of the motor barrel,

a motor piston in the motor barrel having a working area less than that of the power piston,

a pump piston in the pump barrel,

a mandrel connecting the motor piston and the pump piston and having a flow passage extending from the upperside of the motor piston to the underside of the pump piston,

means communicating the flow passage with the interior of the pump barrel above the pump piston,

downwardly-closing valve means in the flow passage above and below the point of exposure of the flow passage to the interior of the pump barrel,

a relief valve opening between the interiors of the motor barrel and the power barrel below the power piston and above the motor piston, and a motor fluid seal carried by the motor barrel and slidably engaging the exterior of the mandrel between the pump piston and the motor piston,

means communicating the interior of the motor barrel with the interior of the power barrel at a point between the motor fluid seal and the motor piston.

9. A well pump as set forth in claim 8, wherein the relief valve includes a body having a passage extending between the interiors of the motor barrel and the power barrel,

a valve seat in the passage,

a valve biased toward closing against the seal toward the motor barrel end of the passage, and a shank on the valve extending into the motor barrel for engagement by the motor piston at the upper end of its stroke for unseating the valve and opening the passage.

l(). A well pump as set forth in claim 6, wherein the motor fluid seal includes a fixed liner held against longitudirral movement and engaging the interior of the motor barrel,

a floating liner mounted to undergo limited longitudinal movement and sealingly engaging the exterior of the mandrel,

and flexible sealing means between the fixed liner and the floating liner.

11. A well pump including,

a power barrel member,

a power piston member in the power barrel member,

one of said power members being reciprocable with respect to the other, a motor barrel,

a power fluid seal carried by the power barrel member for sealing the end of the interior of the power barrel member opposite the power piston member,

a pump barrel rigidly connected to the motor barrel and disposed therebelow, means for anchoring the pump barrel and the motor barrel in a well bore and sealing externally of the pump between the lower end of the pump barrel and the upper end of the motor barrel,

a motor piston in the motor barrel having a working area less than that of the power piston member,

a pump piston in the pump barrel,

a mandrel connecting the motor piston and the pump piston and having a flow passage extending from the upperside of the motor piston to the underside of the pump piston,

means communicating the flow passage with the interior of the pump barrel above the pump piston,

downwardly-closing valve means in the flow passage above and below the point of exposure of the flow passage to the interior of the pump barrel,

and a motor fluid seal carried by the motor barrel and slidably engaging the exterior of the mandrel between the pump piston and the motor piston, means communicating the interior of the motor barrel with the interior of the power barrel member at a point between the motor fluid seal and the motor piston.

12. A well pump including,

a power barrel member,

a power piston member carried by the upper portion of the power barrel member,

one of said power members being reciprocable with respect to the other,

a motor barrel,

a power fluid seal carried by the power barrel member for sealing the end of the interior of the power barrel member opposite the power piston member,

a pump barrel rigidly connected to the motor barrel and disposed therebelow,

means for anchoring the pump barrel and the motor barrel in a well bore and sealing externally of the pump between the lower end of the pump barrel and the upper end of the motor barrel,

a motor piston in the motor barrel having a working area less than that of the power piston member,

a pump piston in the pump barrel having a working area larger than that of the motor piston,

a mandrel connecting the motor piston and the pump piston and having a flow passage extending from the upperside of the motor piston to the underside of the pump piston,

means communicating the flow passage with the interior of the pump barrel above the pump piston,

downwardly-closing valve means in the flow passage above and below the point of exposure of the flow passage to the interior of the pump barrel,

and a motor fluid seal carried by the motor barrel and slidably engaging the exterior of the mandrel between the pump piston and the motor piston,

means communicating the interior of the motor barrel with the interior of the power barrel member at a point between the motor fluid seal and the motor piston.

13. A well pump including,

a power barrel member,

a power piston member in the power barrel member,

one of said power members being reciprocable with respect to the other,

a motor barrel,

a power fluid seal carried by the power barrel member for sealing the end of the interior of the power barrel member opposite the power piston member,

a pump barrel rigidly connected to the motor barrel and disposed therebelow,

means for anchoring the pump barrel and the motor barrel in a well bore and sealing externally of the pump between the lower end of the pump barrel and the upper end of the motor barrel,

a motor piston in the motor barrel having a working area less than that of the power piston member,

a pump piston in the pump barrel,

a mandrel connecting the motor piston and the pump piston and having a flow passage extending from the upperside of the motor piston to the underside of the pump piston,

means communicating the flow passage with the interior of the pump barrel above the pump piston,

downwardly'closing valve means in the flow passage above and below the point of exposure of the flow passage to the interior of the pump barrel,

a relief valve opening between the interiors of the motor barrel and the power barrel member,

and a motor fluid seal carried by the motor barrel and slidably engaging the exterior of the mandrel between the pump piston and the motor piston,

means communicating the interior of the motor barrel with the interior of the power barrel member at a point between the motor fluid seal and the motor piston.

13 14. A well pump as set forth in claim 13, wherein the relief valve includes a body having a passage extending between the interiors of the motor barrel and the power barrel,

a valve seat in the passage,

a valve biased toward closing against the seat toward the motor barrel end of the passage,

and a shank on the valve extending into the motor barrel for engagement by the motor piston at the upper end of its stroke for unseating the valve and opening the passage.

15. A well pump as set forth in claim 11, wherein the motor fluid seal includes a fixed liner held against longitudinal movement and engaging the interior of the motor barrel,

a floating liner mounted to undergo limited longitudinal movement and sealingly engaging the exterior of the mandrel,

and flexible sealing means between the fixed liner and the floating liner.

16. A well pump including,

a power barrel,

a power piston reciprocable in the power barrel,

:1 motor barrel,

8. power fluid seal carried by the power barrel for sea]- ing the end of the interior of the power barrel opposite the power piston,

a pump barrel rigidly connected to the motor barrel and disposed therebelow,

means for anchoring the pump barrel and the motor barrel in a well bore and sealing externally of the pump between the lower end of the pump barrel and the upper end of the motor barrel,

:1 motor piston in the motor barrel having a working area less than that of the power piston,

a pump piston in the pump barrel,

a mandrel connecting the motor piston and the pump piston and having a flow passage extending from the upperside of the motor piston to the underside of the pump piston,

means communicating the flow passage with the interior of the pump barrel above the pump piston,

downwardly-closing valve means in the flow passage above and below the point of exposure of the flow passage to the interior of the pump barrel,

and a motor fluid seal carried by the motor barrel and slidably engaging the exterior of the mandrel between the pump piston and the motor piston,

means communicating the interior of the motor barrel with the interior of the power barrel at a point between the motor fluid seal and the motor piston.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A WELL PUMP INCLUDING, A PUMP BARREL A MOTOR BARREL, FIRST MEANS FOR ANCHORING THE PUMP BARREL AND THE MOTOR BARREL IN A WELL BORE AND SEALING EXTERNALLY OF THE PUMP BETWEEN THE LOWER END OF THE PUMP BARREL AND THE UPPER END OF THE MOTOR BARREL, MEANS FOR EXPOSING THE LOWER END OF THE PUMP BARREL TO THE WELL BORE BELOW THE FIRST SEALING MEANS, MEANS FOR EXPOSING THE UPPER END OF THE MOTOR BARREL TO THE WELL BORE ABOVE THE FIRST SEALING MEANS, A PUMP PISTON IN THE PUMP BARREL, A MOTOR PISTON IN THE MOTOR BARREL, AN ELEMENT CONNECTING THE PUMP PISTON AND THE MOTOR PISTON AND HAVING A FLOW PASSAGE BETWEEN THE UNDERSIDE OF THE PUMP PISTON AND THE UPPERSIDE OF THE MOTOR PISTON, MEANS IN THE FLOW PASSAGE FOR PREVENTING FLUID FLOW DOWNWARDLY FROM THE PASSAGE TO THE UNDERSIDE OF THE PUMP PISTON, MEANS COMMUNICATING THE FLOW PASSAGE ABOVE THE LATTER MEANS WITH THE INTERIOR OF THE PUMP BARREL, SECOND SEALING MEANS SLIDABLY ENGAGING THE ELEMENT CONNECTING THE PUMP PISTON AND THE MOTOR PISTON FOR SEALING OFF BETWEEN THE PUMP BARREL AND THE MOTOR BARREL, A POWER BARREL SURROUNDING THE MOTOR BARREL, THIRD SEALING MEANS CARRIED BY THE POWER BARREL AND SLIDABLY ENGAGING AROUND THE MOTOR BARREL, MEANS COMMUNICATING THE INTERIOR OF THE MOTOR BARREL ABOVE THE THIRD SEALING MEANS WITH THE INTERIOR OF THE POWER BARREL, A POWER PISTON SLIDABLY ENGAGING THE POWER BARREL AND SEALING BETWEEN THE POWER BARREL AND THE MOTOR BARREL ABOVE THE POINT OF EXPOSURE OF THE INTERIOR OF THE MOTOR BARREL TO THE INTERIOR OF THE POWER BARREL, THE POWER PISTON HAVING A WORKING AREA GREATER THAN THAT OF THE MOTOR PISTON, AND MEANS FOR PREVENTING FLUID FLOW DOWNWARDLY FROM THE INTERIOR OF THE MOTOR BARREL INTO THE FLOW PASSAGE. 